Ignition sxstem for fuel burners



Feb. 6, 1951 B. H. SHORT ET AL 2,540,177

IGNITION SYSTEM FOR FUEL BURNERS Filed Nov. 3, 1949 Patented Feb. 6, 1951 U N I T E D S ES I ELNT QF'ICE 2,540,173 I IGNITIQN sysrs-M FOR FUEL BURNERS Brooks ShortandChar-les E. Buck, Anderson} Ind, assignors td-General Motors: Corporation, Detroit; Mich, avcorporationr of lielaware- ApplicationNdvember3, 1949, 'Serial No. 125,351 I 2 Claims. I This invention relates to apparatus for igniting fuel at the burner of an oil heater.

An' object of the invention is to provide. for igniting fuel by the passage electric current across aspark gap in sufficient quantity to provide the necessary heat for igniting fuel such as coal oil or Diesel fuel oil. This is accomplished by the use of an ignition coilby means of which a voltage is builtupto. ,causedischarge across the spark gap, this discharge providing a conducting pathlfo'r' the discharge of a previously'charged condenser having capacity such that the current discharged by it is sufficient to ignite the fuel.

Further objects and advantages of the present invention will be apparent from the following-de- Scription, reference being had to the accompanying drawings wherein a preferredembodiment of the present invention is clearly shown.

In the drawing, the single figure is a wiring diagram of the invention.

The apparatus includes a source of direct current such as battery l grounded at H connected by a switch 42 with a terminal 13 which is connected with the support 14 of a vibrating reed l5 having an armature I6 normally displaced from a magnet core I! surrounded by a coil l8 connected with terminal l3 and with a resistance 19 which is grounded and with a contact 20 normally separated from an engaging contact 2| carried by the reed l5, Reed l5 also carries contacts 23, 25, and 21 normally spaced from and engageable respectively with contacts 22, 24 and 26. Contacts 24 and 26 are connected with the ends of primary windings 28 of a transformer Tl having the center tap 29 grounded. The secondary 30 of transformer TI is connected at one end with a wire 33 and at the other with plate 39 of a tube 35 and with cathode 36 of tube 34. Cathode 31 of tube 35 is connected with round and with a condenser 45 connected with wire 33. Plate 38 of tube 34 is connected with terminal 46 connected with condenser 44 connected with the wire 33. Wire 33 is connected through resistances 42a. and 43 with elements and 4| respectively of the tubes 34 and 35. Tubes 34 and 35 are cold cathode tubes having elements 40 and 4! which start electron emission.

Contact 22 and reed support I4 are connected with a condenser 50 connected with the primary winding 5| of a transformer T2. Secondary winding 52 of transformer T2 is connected with a spark gap 53 and with an auxiliary condenser 49 which is connected by a wire 48 and resistance 41 with output terminal 46 of the power supply (01. ars -24w 2v provided bytransformerTl, tubes 34 and 35and condensers 4'4' and 451' The closing of switch 62 causes the current to flow from the battery 50 to the coil 1'8 thereby causing the armature It to move a distance into alignment with the core 1'! such as to efiect engagement of contacts 24', 25 and contacts 20, 2'1. When'contacts 2'fi',-,2lengage the coil I8 is short circuited so that the reed l5'is permitted toswing in the other direction to efiect engagement of contacts 22', 2'3 and 20, 21'. The separation of contacts 20 and 2| having been effected -coil"l'8' is energized again to repeat the operation. Therefore, as contacts 24, 25' and 23, 21 alternately engage current passes from the battery alternately into the halves of the primary winding 28to obtain through the operation of the transformer TI and the rectifier tubes 34 and 35 a relatively high voltage at terminal 53, for example 1500 volts D. C., which is sufficient for charging the condenser 49 in the time allowed.

While contacts 26, 21 are engaged, current flows in a direction indicated by arrow 28a in the left half of winding 28 thereby inducing 2, voltage in Winding 30. Assuming that wire 32 is then positive, current flows through tube 35 and to one plate of condenser in the direction of arrow 45a and by condenser action to wire 33. While contacts 24 and 25 are engaged, current flows in the direction indicated by arrow 28b in the right half of winding 28 and a voltage is induced in winding 30 such that wire 33 is positive; and current flows to one plate of condenser 44 in the direction ofarrow 44a and by condenser action to tube 34 and to wire 32. A buffer condenser 3| absorbs transient voltages when vibrator contacts open. Since condensers 44 and 45 are in series and in assisting relation, the potential at terminal 46 is the sum'of the potentials of condensers 44 and 45 and attains the required value to charge condenser 49.

While contacts 22, 23 are engaged, current builds up in winding 3|. W'hen contacts 22, 23 disengage, with the assistance of condenser 50 an abrupt reduction in current in winding 3| is efi'ected and a voltageis induced in winding 52 (for example 20,000 volts) sumcient tobreak down the gap at the spark plug 53 and the energy of winding 52 discharges across the gap thereby providing a conducting path for the discharge of condenser 49 which has capacity such that the current discharged will supply heat sufficient to ignite. the fuel. The discharge of condenser 49 continues until the voltage of that condenser decreases below the voltage (1000 volts for example) sufficient to maintain the are at the spark plug gap and will continue for a time after the energy of winding 52 has been dissipated.

Without the condenser 49, the discharge of ignition coil T2 appears as a pale blue spark of relatively short duration. With the condenser 49, discharging through the path established by the coil T2, there appears a reddish ball of fire. In other words, the spark is fatter and hotter.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. An ignition system for a fuel oil burner comprising a spark plug, an ignition coil having a secondary winding in series with the spark plug and having a primary winding, a current source, a vibrator operated by the current source for intermittently connecting theprimary winding with the current source, a condenser in series with the secondary winding and the spark plug, a transformer having a secondary winding and a center-tapped primary winding, means operated by the vibrator for connecting the current source alternately with the halves of the primary winding of the transformer, two rectifier tubes having plates and cathodes, a connection between one end of the transformer secondary winding and the plate of one tube and the cathode of the other tube, parallel circuits connected with the other end of the transformer, one parallel circuit, including a condenser in series with the cathode of said one tube and the other parallel circuit including a condenser in series with the plate of said other tube whereby the potentials of the condensers in said parallel circuits are in assisting relation, and a circuit including a resistance and all three condensers in series.

2. An ignition system for a fuel oil burner comprising a spark plug, an ignition coil having a secondary winding in series with the spark plug and having a primary winding, a condenser in series with the secondary winding and the spark plug, a transformer having a primary, winding and a secondary winding, a direct current source, means for connecting the current source intermittently with the primary winding of the igni tion coil and with the primary winding of the transformer, two rectifier tubes having plates and cathodes, a connection between one end of ;the transformer secondary winding and the said other tube whereby the potentials of the condensers in said parallel circuits are in assisting relation, and a circuit including a resistance and all three condensers in series.

BROOKS H. SHORT. CHARLES E. BUCK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,955,520 Vawter Apr. 17, 1934 2,470,413 Ramsay May 17, 1949 

